Molecular Clouds Surrounding Supernova Remnant G43.9+1.6: Associated and Non-associated

TL;DR

This study investigates the molecular environment of supernova remnant G43.9+1.6, identifying a specific associated molecular cloud component at 50 km/s and clarifying the non-association of another component at 5 km/s through CO line observations.

Contribution

The paper provides new evidence linking the SNR G43.9+1.6 to a molecular cloud at 50 km/s and clarifies the non-association at 5 km/s using detailed CO spectral analysis.

Findings

The SNR is associated with the 50 km/s molecular cloud component.

No dynamical disturbance was found for the 5 km/s component.

The SNR is estimated to be at a distance of about 3.1 kpc.

Abstract

Many supernova remnants (SNRs) are considered to evolve in molecular environments, but the associations between SNRs and molecular clouds (MCs) are often unclear. Being aware of such ambiguous case, we report our study on the molecular environment towards the SNR G43.9+1.6 by CO line observations. We investigated the correlations between the SNR and MCs at different velocities, and found two velocity components, i.e. $\sim$5 km s$^{-1}$ and $\sim$50 km s$^{-1}$ velocity components, showing spatial correlations with the remnant. However, no dynamical evidence of disturbance was found for the $\sim$5 km s$^{-1}$ velocity component. At the distance of the $\sim$5 km s$^{-1}$ velocity component, either near or far distance, the derived physical parameters are unreasonable too. We conclude that the SNR is not associated with the $\sim$5 km s$^{-1}$ velocity component, and their spatial correlation is just a chance correlation. For the $\sim$50 km s$^{-1}$ velocity component, dynamical evidence of disturbances, as well as the spatial correlation, indicate that it is associated with the SNR. We found that all the CO spectra extracted from the molecular clumps distributed along the border of the remnant are with broadened components presented, which can be fitted by Gaussian functions. By further analysis, we suggest that the SNR is at a near kinematic distance of about 3.1 kpc.